Technetium Tc 99m Medronate (Systemic)

Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).

Category:

Diagnostic aid, radioactive (bone disease)—

IndicationsAccepted

Skeletal imaging, radionuclide—Technetium Tc 99m medronate is indicated as a skeletal imaging agent to delineate areas of abnormal osteogenesis, such as those that occur with metastatic bone disease, Paget's disease, arthritic disease, osteomyelitis, and fractures. {01}{16}{17}{22}{23}{27}{28}

Physical Properties

Nuclear data:

Radionuclide
(half-life)

Decay
constant

Mode
of
decay

Principal
photons
emissions
(keV)

Mean
number of
emissions/
disintegration
(³0.01)

Tc 99m
(6.0 hr)

0.1151 h -1

Isomeric
transition to
Tc 99

Gamma
(18)

0.062

Gamma
(140.5)

0.891

Pharmacology/Pharmacokinetics

Mechanism of action/Effect:

Exact mechanism is not known. It is generally accepted that technetium Tc 99m medronate localizes on the surface of hydroxyapatite crystals by a process termed chemisorption, with blood flow and/or blood concentration being most important in the delivery of the agent to sites of uptake. Visualization of osseous lesions is possible since skeletal uptake of technetium Tc 99m medronate is altered in areas of abnormal osteogenesis. {16}{17}{27}{30}Distribution:

Rapidly distributed in and cleared from blood after intravenous administration, with about half the administered activity normally accumulating in the skeleton within 3 to 4 hours after intravenous administration {02}{16}{17}. May also locate within infarcted myocardial cells or other regions of soft tissue necrosis or calcification. Minimal uptake by soft tissue organs, except calcified cartilage, blood vessels, and kidneys. {16}{17}{18}{19}{21}{24}{25}Time to radioactivity visualization:

The possibility of pregnancy should be assessed in women of child-bearing potential. Clinical situations exist where the benefit to the patient and fetus, based on information derived from radiopharmaceutical use, outweighs the risks from fetal exposure to radiation. In these situations, the physician should use discretion and reduce the radiopharmaceutical dose to the lowest possible amount. {12}

Although it is not known whether technetium Tc 99m medronate is distributed into breast milk, it is known that Tc 99m as free pertechnetate is distributed into breast milk. Based on the assumption that the Tc 99m in breast milk is in the form of pertechnetate and based on the effective half-life of the radionuclide in breast milk, the daily volume of milk, a dose factor relating the radionuclide to its critical organ (thyroid) in the nursing infant, and the maximum permissible dose to that organ, a guideline has been proposed. According to this guideline, it has been calculated that nursing can be safely resumed when the concentration in breast milk reaches 30.3 × 10 -4 megabecquerels (8.2 × 10 -2 microcuries) per mL. This level of activity is probably reached, in the majority of patients, within 12 to 24 hours after administration of technetium Tc 99m–labeled radiopharmaceuticals. {11}Pediatrics

Diagnostic studies performed to date using technetium Tc 99m medronate have not demonstrated pediatrics-specific problems that would limit its usefulness in children. However, there have been no specific studies evaluating the safety and efficacy of technetium Tc 99m medronate in pediatric patients. When this radiopharmaceutical is used in children, the diagnostic benefit should be judged to outweigh the potential risk of radiation. {10}{12}

Geriatrics

Appropriate studies on the relationship of age to the effects of technetium Tc 99m medronate have not been performed in the geriatric population. However, no geriatrics-specific problems have been documented to date.Drug interactions and/or related problems
See Diagnostic interference.Diagnostic interference
The following have been selected on the basis of their potential clinical significance (possible effect in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):

With results of this test

Due to other medications
Antacids, aluminum-containing (high blood concentrations of aluminum ion, which may occur in patients with gastrointestinal obstruction or impaired renal function, may cause localization of technetium Tc 99m medronate in the liver {03})

Etidronate (etidronate may interfere with bone uptake of technetium Tc 99m medronate; a 2-week period after discontinuation of etidronate therapy is recommended before performance of a bone scan with technetium Tc 99m medronate {04}{20}{31}{32})

With results of other tests
Brain imaging (brain scans using sodium pertechnetate Tc 99m may result in high blood background activity when performed after a bone scan using technetium Tc 99m medronate, which contains stannous ions; to avoid this potential diagnostic interference, brain scan may be performed prior to bone scan or with a brain imaging agent other than sodium pertechnetate Tc 99m [e.g., technetium Tc 99m pentetate] {28}{30})

Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).

Risk-benefit should be considered when the following medical problem exists
Sensitivity to the radiopharmaceutical preparation

Side/Adverse Effects
The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:Those indicating need for medical attentionIncidence less frequent or rareAllergic reaction (skin rash, hives, or itching{01}{16}{17})

Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Radiopharmaceuticals (Diagnostic).

In providing consultation, consider emphasizing the following selected information (» = major clinical significance):Description of use
Action in the body: Accumulation of radioactivity in bone

Retention of radioactivity in bone allows visualization of lesions

Small amounts of radioactivity used in diagnosis; radiation received is low and considered safeBefore having this test» Conditions affecting use, especially:Sensitivity to the radiopharmaceutical preparation

Pregnancy—Technetium Tc 99m (as free pertechnetate) crosses placenta; risk to fetus from radiation exposure as opposed to benefit derived from use should be considered

Breast-feeding—Not known if technetium Tc 99m medronate is distributed into breast milk, but Tc 99m as free pertechnetate is distributed into breast milk; temporary discontinuation of nursing may be recommended because of risk to infant from radiation exposure

Use in children—Risk from radiation exposure as opposed to benefit derived from use should be considered

Preparation for this test
Special preparatory instructions may be given; patient should inquire in advance

Increasing intake of fluids and voiding frequently after injection and before test begins in order to minimize radiation dose to bladder

Voiding just prior to imaging for best test resultsPrecautions after having this test
Increasing intake of fluids and voiding frequently for 4 to 6 hours after test to minimize radiation dose to bladder

General Dosing Information
Radiopharmaceuticals are to be administered only by or under the supervision of physicians who have had extensive training in the safe use and handling of radioactive materials and who are authorized by the Nuclear Regulatory Commission (NRC) or the appropriate Agreement State agency, if required, or, outside the U.S., the appropriate authority.

The patient should increase intake of fluids and void frequently following the administration of technetium Tc 99m medronate injection, and for 4 to 6 hours after the imaging procedures are completed, to minimize radiation dose to the bladder. {01}{17}

Voiding is also recommended immediately prior to imaging procedures to reduce background interference that may result because of the accumulation of the agent in the bladder.

Manufacturer's package insert or other appropriate literature should be consulted for optimal times when imaging should be performed.Safety considerations for handling this radiopharmaceutical
Improper handling of this radiopharmaceutical may cause radioactive contamination. Guidelines for handling radioactive material have been prepared by scientific, professional, state, federal, and international bodies and are available to the specially qualified and authorized users who have access to radiopharmaceuticals. {33}

10 mg medronic acid and not less than 0.60 mg stannous chloride dihydrate (maximum total tin expressed as stannous chloride dihydrate 1.10 mg), in a lyophilized form and under nitrogen atmosphere, per 10-mL reaction vial (Rx) [TechneScan MDP]

10 mg medronic acid and not less than 0.60 mg stannous chloride dihydrate (maximum total tin expressed as stannous chloride dihydrate 1.10 mg), in a lyophilized form and under nitrogen atmosphere, per 10-mL reaction vial (Rx) [AN-MDP]

10 mg medronate disodium and 0.85 mg stannous chloride dihydrate, in a lyophilized form and under nitrogen atmosphere, per reaction vial (Rx) [Osteolite]

Note: Before radiolabeling, the kit may be stored at or below room temperature. {16}{17}

Preparation of dosage form:
To prepare injection, an oxidant-free sodium pertechnetate Tc 99m solution is used. See manufacturer's package insert for instructions. {17}Stability:
Injection should be administered within 6 hours after preparation. {16}{17}Incompatibilities:
If oxidants such as peroxides and hypochlorites are present in the sodium pertechnetate Tc 99m used for labeling, the final preparation may be adversely affected and should be discarded.Note: Caution—Radioactive material.

Task Group of Committee 2 of the International Commission on Radiological Protection. Annals of the ICRP. ICRP Publication 53—Radiation dose to patients from radiopharmaceuticals. New York: Pergamon Press, 1988: 215.

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